Top Gear is not a show that can be fronted by one person, it never has been and there is no reason to think it can now. There is a reason that they have sold the three presenter format around the world and that's because it works. More personally I and thousands of others out a lot of time and effort into writing and filming audition piece son the promise that there was a chance one of us might be lucky enough to get a chance to work on the show we love so much and ten weeks or so on from the closing date we get this. Even Clarkson for all his bombast and ego wasn't deluded enough to think he could carry the show on his own.
That said if you re-read more carefully it does say that it's a one man thing currently; I doubt very much I've it will remain that way, partly because I don't believe it would work but also because the burden of responsibility would be far too great for any one person to shoulder on their own.
I take you never heard anything back about your submission?